Ni@COF1-Catalyzed Finkelstein and retro-Finkelstein reactions are reported! Comparative studies reveal that a nickel-functiontionalized olefin-linked covalent organic framework (Ni@COF1) outperforms its reduced analog (Ni@COF1R) in visible-light-driven halide exchange reactions. This robust catalyst exhibits high efficiency and broad functional group compatibility and enables late-stage functionalization of diverse drug scaffolds.

Abstract

Covalent organic frameworks (COFs) are emerging as a versatile class of hosts for heterogeneous photocatalysis. Herein, we present a nickel-decorated pyrene- and bipyridine-based olefin-linked COF (Ni@COF1) as a robust and recyclable catalyst for visible-light-driven aromatic Finkelstein and retro-Finkelstein reactions. The extended π-conjugation within the COF framework enhances light absorption, promotes charge transport, and facilitates in situ Ni(0) generation from the pre-installed Ni(II) centers. Compared to its reduced counterpart (Ni@COF1R), Ni@COF1 exhibits remarkable catalytic performance. The methodology enables selective halide exchange, broad functional group compatibility, and late-stage diversification of eight bioactive molecules and nine pharmaceutical motifs. Furthermore, a gram-scale reaction with batch and continuous flow conditions underscores its scalability and synthetic utility. The catalyst is robust and recycled five times without any loss of catalytic activity, reaching a total turnover number >850. These results highlight the significance of olefin-linked COFs in advancing sustainable photocatalysis and expanding their role in fine chemical synthesis.